Can confirm that this is happening to me. No mods, repaired game, city hall is open, etc. I could have sworn I had it work once though, not sure what was up with that.
Okay, it works for me if I get my sims engaged in game. Not if I set them as fiance in CAS.
Had my sims arrive at 4:33, so City Hall was definitely open. First I thought they must be too far away when I tried to use the Get Married interaction - they kept getting distracted with practicing singing and playing the violin. So I teleported them in front of city hall again, had the bride hold her bouguet and clicked get married. They kissed, then nothing.
Then I thought maybe the bouquet was in the way and had her put it away. Failed again - this time the groom tried to run off and greet a friend. At that point I figured it must be too close to 6pm - 5.50 or so - and gave up.
Here's my save if you still need one.
https://drive.google.com/file/d/1gSvgkG4laMtGWA-tEjpyKcR-yv8HDPMp/view?usp=sharing
